1. 1 © ACRI-ST, all rights reserved – 2012 Galactic noise model adjustment Jean-Luc Vergely (ACRI-ST) Jacqueline Boutin (LOCEAN) Xiaobin Yin (LOCEAN)

2. 2 © ACRI-ST, all rights reserved – 2012 Issue : GN correction. Aim of this study : To better understand rugosity in L band To estimate the GN corrections for some operating points (WS, theta) and to cross check with the current model implemented in the L2OS processor.

3. 3 © ACRI-ST, all rights reserved – 2012 Inversion of the forward model Data : SMOS Tbgal_refl_X and Tbgal_refl_Y = TB L1c – flat sea and roughness contribution – OTT – atmospheric contribution Forward model : With b=cos²(a) or b=sin²(a), a being the rotation angle ground->antenna Inversion shall be done at the antenna level : bayesian approach as for SSS retrieval. UNKNOWN : and

4. 4 © ACRI-ST, all rights reserved – 2012 SMOS data selection : reprocessed data 30 descending half orbits in the south pacific in the period 09/2011 – 11/2011 => strong galactic signal is expected. 11 ascending half orbits in the south pacific in the period 03/2010 – 04/2010 => strong galactic signal is expected. Selection of data : no contamination by land, TB valid, geometric rotation < 10° : TBH and TBV processed independently.

5. 5 © ACRI-ST, all rights reserved – 2012 Inverse scheme Retrieval :  non parametric approach.  Axisymmetry of the bistatic coefficients. Add new constraints in the retrieval scheme:  forcing the normalization of the bistatic coefficients.  Possibility to add a bias (as an OTT)  Use of asc and desc orbits

6. 6 © ACRI-ST, all rights reserved – 2012 Retrieval results polar H (ascending) RH around 0.72 as expected Strong negative bias. OTT issue ? Dynamic only for WS = 3m/s

7. 7 © ACRI-ST, all rights reserved – 2012 Retrieval results polar V (ascending) Strong negative bias.

8. 8 © ACRI-ST, all rights reserved – 2012 Retrieval results Comparison with AUX_GAL2 (ascending) Differences due to the bias (always negative) ? From non parametric approach AUX_GAL2 new

9. 9 © ACRI-ST, all rights reserved – 2012 Retrieval results polar H (descending)

10. 10 © ACRI-ST, all rights reserved – 2012 Retrieval results polar V (descending) Strong negative bias.

11. 11 © ACRI-ST, all rights reserved – 2012 Retrieval results Comparison with AUX_GAL2 (descending) Better than ascending for H pol. Difference in V pol due to the bias. AUX_GAL2 new From non parametric approach

12. 12 © ACRI-ST, all rights reserved – 2012 Retrieval results Comparison with old AUX_GAL2 (descending) NEW AUX_GAL2OLD AUX_GAL2 With normalisation From non parametric approach AUX_GAL2 new From non parametric approach (old data) AUX_GAL2 old No normalisation

13. 13 © ACRI-ST, all rights reserved – 2012 Conclusions Results depend on OTT. Chi2 too high. Strong dynamic for WS=3 m/s only. Low response for ascending orbits -> to be done with extended selection. Solution is lower than the new AUX_GAL LUT Better coherence for descending orbits, H pol. Problem with the normalization and the constant correction ? Data set to be increased, at least for ascending orbits.